This invention relates generally to color masking and specifically to such systems which employ the multiplication capabilities of electro-optical imaging devices to achieve in real-time that which is usually a relatively time consuming process.
Color copying has become increasingly important in recent years because of changes in public acceptance of, and demand for, color information. The pressures created by these demands have resulted in numerous technological advances in the color reproduction arts, among which is that set forth in the instant disclosure.
Due to the inability of readily available and economic dyes to adequately reflect colors, it is necessary that some compensation or color correction be made to reduce the amount of specific pigments in specific areas -- a compensation which is most often accomplished by the process known as color masking. Many color masking techniques are known in the art as, for example, those described in The Focal Encyclopedia of Photography, Vol. II, pp. 921-927, W. & J. Mackay & Co., Ltd., Chatham, England, 1965, or by Yule in Principles of Color Reproduction, John Wiley & Sons, Inc., New York, 1967. These techniques include the well known photographic process of masking color separation negatives or positives, with other negatives or positives to vary the density of the specific color components.
Additional related techniques include the use of electronic color scanners which simultaneously or individually produce color separations. These devices scan the subject along very narrow lines using a small light beam and, through lenses and electronic gear obtain all of the information needed to separate colors and make such corrections as are necessary.
As mentioned above, the instant invention employs a broad class of imaging members which record optical images by an imagewise distribution of photo-generated voltages or current acting upon a voltage or current-alterable recording medium. Typically, in these members, imagewise activating radiation incident on a photoconductor allows charge carriers to move in an external electric field. These charge carriers interact with a voltage or current-sensitive member which in turn modulates light.
U.S. Pat. No. 2,896,507 describes an imaging member which includes a photoconductive layer on an elastically deformable layer sandwiched between a pair of electrodes, one of which is a thin metallic layer overlying the deformable layer. In operation, imagewise activating radiation is directed upon the member and an electrical field is established across the photoconductive and deformable layers thus causing these layers to deform in image configuration. The member is described as being capable of functioning as an image intensifier since the deformation image may then be read out with a high intensity light source and a Schlieren-type optical system.
Recently, a major advance in the art was made by Sheridon who disclosed the Ruticon (derived from the Greek words "rutis" for wrinkle and "icon" for image) family of imaging member wherein the voltage sensitive light modulating recording medium comprises a deformable elastomer layer and a photoconductive material may be provided as a separate layer or incorporated in the elastomer layer. For a detailed description of the Ruticon devices, see IEEE Transactions On Electron Devices, September 1972, and U.S. Pat. No. 3,716,359. Various different embodiments for establishing an electric field across the elastomer layer are described.
Sheridon discloses (U.S. Pat. No. 3,716,359) several embodiments of electro-optical imaging members and several variations upon ther useful application. The instant invention employs these members in a novel fashion to achieve results comparable to prior art color masking techniques.